non-invasive ventilation dr liam doherty, consultant respiratory physician, bon secours, cork
TRANSCRIPT
Non-invasive Ventilation
Dr Liam Doherty,Consultant Respiratory Physician,Bon Secours, Cork
Positive Airway Pressure
CPAP = continuous positive airway pressure
BiPAP = Bilevel positive airway pressure = Inspiratory pressure (IPAP)
and expiratory pressure (EPAP)
Why?
Invasive ventilation
SedatedCan’t speakCan’t eatHigh infection riskIncreased bleeding riskBarotraumaLimited ICU beds
Non-invasive ventilation
Not sedatedCan speakCan eatLow infection riskAvailable on well-supervised medical wards
How does it work?
In summary
Stents airway
Recruitment of alveoli
Decreases right to left intrapulmonary shunting
Decreases work of breathing
Overcomes PEEPi
Lowers left ventricular transmural pressure reducing afterload and increasing cardiac output
Who gets NIV?
Acute Type 2 Respiratory failure
COPD, pH <7.35 despite maximum Rx on controlled O2Cardiogenic pulmonary oedema with hypoxia. Decompensated obstructive sleep apnoea. Chest wall trauma who remain hypoxic. (CPAP)Diffuse pneumonia who remain hypoxic despite maximum Rx (CPAP)Weaning from invasive ventilation.
Who can’t have NIV?
Recent facial or upper airway/upper GI surgery, Facial burns or trauma, Fixed obstruction of the upper airway, Vomiting.Inability to protect the airway, Copious respiratory secretionsLife threatening hypoxaemia, Severe co-morbidity, Confusion/agitation, Bowel obstruction.
Which ventilator
Types of NIV
Negative pressure ventilation e.g. “iron-lung”, tank, shell, cuirass, rocking bed,
pneumo-belt
Positive pressure ventilation Pressure limited (CPAP, Bilevel PAP) Volume limited
N.B. Diaphragm-pacing, glosso-pharyngeal breathing,
cough insufflator-exsufflator
Which interface
How do you commence NIV?
Monitoring progress
OximetryRespiratory ratePatient comfortPCO2
Patient-ventilator synchronisation
Give breaks for drinks/foodKeep on for as long as possible (2 days+)
When things go wrong!
Is ventilation inadequate?
Observe chest expansion
Increase target pressure (or IPAP) or volume
Consider increasing inspiratory time
Consider increasing respiratory rate (to increase minute ventilation)
Consider a different mode of ventilation/ventilator, if available
Is the patient synchronising with the ventilator?
Observe patient
Adjust rate and/or IE ratio (with assist/control)
Check inspiratory trigger (if adjustable)
Check expiratory trigger (if adjustable)
Consider increasing EPAP (with bi-level pressure support in COPD)
Downside to NIV
Horrendous to wear
Can’t talk
Can’t eat/drink
Can’t sleep
Agitation, claustrophobia
Poor synchrony
Delays intubation
Final messages
Give appropriate oxygen!
Non-invasive ventilators just blow air
Try to synchronise ventilator to patient i.e. ventilator should support normal ventilation
When in doubt use CPAP
NIV doesn’t work for everyone
(30% failure rate)
Never forget need for intubation!